The present invention relates to an antenna device adapted for use with a portable wireless device of which a cellular phone is a representative example, and a portable wireless device.
A conventional example of an antenna device used in a portable wireless device of which a cellular phone is a representative example is arranged on the top of a housing and adapted to be withdrawn therefrom. This type of antenna device displays excellent antenna characteristics and is adapted for use as a portable unit since the antenna device can be stored in the housing when not in use and withdrawn from the housing when in use.
FIG. 10 is a rear view showing the structure of a cellular phone using a conventional antenna device. The conventional antenna device is provided for example on the left side of the cellular phone when viewed from the rear surface of the cellular phone. The antenna device is provided with a tubular excitation antenna 90 and a columnar helical antenna 91. The excitation antenna 90 is fixed to an antenna mounting section 92a which is a section of the housing 92. The helical antenna 91 can displace in an interior space of the excitation antenna 90 along an axial direction A. An antenna support shaft 93 is mounted on the lower end of the helical antenna 91. The antenna support shaft 93 is supported in a predetermined position by a holder 94 which is fixed to the housing 92.
In this manner, the antenna device has two antenna components of the excitation antenna 90 and the helical antenna 91 and each antenna is mounted on the housing 92 at respectively different positions. That is to say, the excitation antenna 90 is supported by the antenna mounting section 92a and the helical antenna 91 is supported by the holder 94. Therefore, the operation of the antenna device can not be confirmed until after attaching the antenna device to the housing. That is to say, it is not possible to confirm the operation of the antenna device independently.
The helical antenna 91 can be stored in a storage position as shown by the broken line in FIG. 10 from the position shown by the two-dot chain line. Furthermore, the helical antenna 91 can be drawn out from the storage position to the position shown by the two-dot chain line. In this time, the antenna support shaft 93 displaces together with the displacement of the helical antenna 91. Thus, when the helical antenna 91 is stored in the storage position, the antenna support shaft 93 extends below the excitation antenna 90.
As a result, in the conventional antenna device, a region directly below the excitation antenna 90 must be provided as a displacement region for the antenna support shaft 93. In other words, the displacement region for the antenna support shaft 93 splits the storage region for the battery pack 95 attached to the rear surface of the cellular phone. Thus, the problem has arisen that increases in the capacity of the rechargeable battery 96 are limited as a result of limitations on the size of the rechargeable battery 96 mounted in the battery pack 95.
FIG. 11 is a cross sectional view showing the internal structure of a cellular phone using the conventional antenna device as viewed from the bottom side thereof. As clearly shown in FIG. 11, the designated region for the rechargeable battery 96 avoids a displacement region for the antenna support shaft 93 in order to maintain the displacement region for the antenna support shaft 93. As a result, difficulties in increasing the capacity of the chargeable battery 96 have been encountered. This problem is particularly conspicuous with respect to antenna devices used in a satellite cellular phone which consumes relatively large amount of electrical power.
The present invention is proposed to solve the above problems and has the object of providing an antenna device which is adapted for use with a portable wireless device and which allows confirmation of the operation independently.
The present invention has the further object of providing a portable wireless device which can use the above antenna device even when a displacement region for a moveable antenna is not provided directly below the antenna device.
In order to achieve the above objects, an antenna device of the present invention comprises a first cylindrical antenna and a second cylindrical antenna which is fittingly inserted into the first antenna to allow displacement and electrical connection to the first antenna. A shaft which extends along a displacement direction of the second antenna is provided in an internal space of the first antenna. An antenna retaining section is provided at a fixed position on the shaft in order to retain the second antenna to a fixed displacement position.
According to the present invention, the shaft is arranged in an internal space of the first antenna and the second antenna can displace along the shaft. Thus, it is possible to integrate these antenna devices into a single unit. As a result, it is possible to confirm operation of the antenna device independently before mounting the antenna device onto the housing of the portable wireless device.
Furthermore, the second antenna displaces along the shaft provided in the internal space of the first antenna. Therefore, even when the second antenna is stored in a storage position, it is not necessary to maintain a displacement region for components related to the antenna in the region directly below the first antenna. As a result, when the antenna device is used in a portable wireless device, it is possible to use the region directly below the first antenna as a part of the designated region for the rechargeable battery. Thus, the capacity of the rechargeable battery can be increased.